Start communicating by recalling a shared experience with them. Connect to them in a warm way, send a note, ask them out for coffee. Be genuine. Call them up and check on them. Find people you can connect your network with and help them. They will return the favor. Most importantly, "build the connection first, do business later." — Dr. Cherry Collier, Personality Matters, INC.

2. Use a Custom Invitation Via LinkedIn

LinkedIn is one of the best professional networking platforms available. Update your profile and start reaching out to former colleagues using a custom invitation. It's a great way to reconnect, get in touch, and stay in touch without the need to offer any apologies for why you've been missing-in-action. — Jackie Nagel, Synnovatia